Sunamp UniQ HW+i experience? Charge via ASHP?

[PeterW]

31 minutes ago, ProDave said:

All I would add, is my preference is separate 2 port valves rather than a 3 port.

 

With an ASHP having a permanently open circuit stops over temperature trips when the pump over runs after the valve closes. You can use a differential bypass valve but ASHP are less tolerant of over temperature and over pressure situations on the whole so a diverter is one less thing to wire, and a simple solution to a permanently open flow path 

[ProDave]

57 minutes ago, PeterW said:

 

With an ASHP having a permanently open circuit stops over temperature trips when the pump over runs after the valve closes. You can use a differential bypass valve but ASHP are less tolerant of over temperature and over pressure situations on the whole so a diverter is one less thing to wire, and a simple solution to a permanently open flow path 

I assume you are referring to a 2 position 3 port valve, not that "work of the devil" the mid position 3 port valve?  If so I would tend to agree with you.

[PeterW]

It’s a 3 port diverter valve, not a 3 port mid position valve. They come with a microswitch that can be useful. 

[jfb]

3 hours ago, PeterW said:

Not much more to it to be honest ..??

i'm away for the weekend but when I get back I will try to make more sense of this so I understand it better!

[Triassic]

So what is the current thinking regarding the best set up for a Sunamp?

[oranjeboom]

On 03/09/2019 at 17:55, JSHarris said:

In essence, the Sunamp doesn't really start to store much heat at all until it is heated to the phase transition temperature of the PCM, so heating it to, say, 50°C won't do much, it might put around 10% of the heat capacity into the thing, if that.  The major part of the heat stored comes from the phase change, and that won't start until the PCM is heated to about 58°C, and to do that probably needs a flow temperature of over 60°C, perhaps around 65°C, because there will be a small temperature loss across the internal heat exchanger, and through the melted PCM close to the heat exchanger.

 

So I think I have decided that using a HT ASHP to charge a Sunamp Dual and my UFH does not make sense. So will probably stick with:

•  eDual for DHW (charged by grid and PV)
• low temp ASHP for UFH

However, I still am thinking about getting the ASHP sitting there doing nothing when there is no call for heat. So with an additional Dual (PCM58, only fed by a heat source only) it's clear that using a low temp ASHP won't get the water to a high enough temp for the sunamp to re-charge. But what about getting a Willis heater in the mix?

 

ASHP temp (35c) -> Willis heater (+30c) -> Sunamp (65c)

 

Means that I get the water efficiently heaterd to 35c with a decent COP but obviously grid (in winter) to charge the willis. Could a willis even be set up in this arrangement or would I still need a tank/cylinder? Was hoping that the willis could simply be integrated into the plumbing between the ASHP and the Sunamp but presume this would depend on the flow rate that the Willis needs?

 

Would just be nice to have the use of the ASHP when it's not needed by the UFH. the Dual sunamp can then be charged for DHW (and UFH if needed).

[Jeremy Harris]

28 minutes ago, oranjeboom said:

 

So I think I have decided that using a HT ASHP to charge a Sunamp Dual and my UFH does not make sense. So will probably stick with:

•  eDual for DHW (charged by grid and PV)
• low temp ASHP for UFH

However, I still am thinking about getting the ASHP sitting there doing nothing when there is no call for heat. So with an additional Dual (PCM58, only fed by a heat source only) it's clear that using a low temp ASHP won't get the water to a high enough temp for the sunamp to re-charge. But what about getting a Willis heater in the mix?

 

ASHP temp (35c) -> Willis heater (+30c) -> Sunamp (65c)

 

Means that I get the water efficiently heaterd to 35c with a decent COP but obviously grid (in winter) to charge the willis. Could a willis even be set up in this arrangement or would I still need a tank/cylinder? Was hoping that the willis could simply be integrated into the plumbing between the ASHP and the Sunamp but presume this would depend on the flow rate that the Willis needs?

 

Would just be nice to have the use of the ASHP when it's not needed by the UFH. the Dual sunamp can then be charged for DHW (and UFH if needed).

 

I'm not convinced that you could get the controls to work with the Willis heater in the mix.  The eDual needs a boiler, or other heat source, that can deliver a fixed temperature of around 65°C in order to charge, and the heat source side control system only provides a simple call for heat relay to tell the boiler to fire up.  It relies on the boiler holding the flow temperature at around 65°C, and that's not going to be easy with a Willis heater, as the flow rate will need to be modulated right down somehow.  A small, variable speed pump, together with some flow and temperature sensors and a control system, rather like that used in the Sunamp PV might do it, but it would need a bit of playing about to get it to regulate properly and deliver water at the right temperature to the Sunamp.

 

The electrically heated model (grid or PV)  has a controller that manages the charge from either PV or the grid, and works fine we've found.  There's real no merit in firing up the heat pump for pre-heat I've found, and if doing it again I'd leave out the buffer, flow switch, heat exchanger etc I installed, as it just over-complicates things for the sake of saving a few pounds a year on the hot water bill (saves less than a tenner a year I reckon).

[ProDave]

11 minutes ago, JSHarris said:

 

I'm not convinced that you could get the controls to work with the Willis heater in the mix.  The eDual needs a boiler, or other heat source, that can deliver a fixed temperature of around 65°C in order to charge, and the heat source side control system only provides a simple call for heat relay to tell the boiler to fire up.  It relies on the boiler holding the flow temperature at around 65°C, and that's not going to be easy with a Willis heater, as the flow rate will need to be modulated right down somehow.  A small, variable speed pump, together with some flow and temperature sensors and a control system, rather like that used in the Sunamp PV might do it, but it would need a bit of playing about to get it to regulate properly and deliver water at the right temperature to the Sunamp.

 

And I expect the problem with trying to do that would be it would result in a water flow rate that was too low for the ASHP.  Our LG one in particular demands quite a high water flow rate otherwise it will shut down with an error code.

 

Typically when our ASHP is heating the hot water tank, it runs with a return temperature about 6 or 7 degrees lower than the flow temperature.  This idea would need a return temperature to the ASHP of abour 30 degrees lower than the flow temperature (from the Willis)   That is just not going to happen.

[Ed Davies]

3 hours ago, oranjeboom said:

ASHP temp (35c) -> Willis heater (+30c) -> Sunamp (65c)

 

But the return temperature out of the Sunamp will be something in the 50's °C which will be too high to cycle back into the ASHP usefully. Both because that's intrinsically how Sunamps work and also because of the flow rate reasons @ProDave points out.

 

I think the only plausible scheme like this is to have a buffer tank which the ASHP heats to something like 30 to 40 °C and use that to preheat the DHW flowing into the Sunamp so that the Sunamp only has to heat the water through the last 10 or 20 °C. @JSHarris has a scheme like this but doesn't use it a lot.

 

If you're going to have a buffer tank for your UFH anyway for flow/cycling reasons then using that to preheat the DHW might make sense. I have similar thoughts about a pre-heat buffer tank heated by solar thermal followed by a Sunamp heated by PV. That'd allow the solar thermal to operate at lowish temperature where it works more efficiently and the PV to do the just the last bit of heating of the DHW up to the use temperature where you want to use the least electricity for the purpose possible.

[Dan F]

@oranjeboom FYI, I've been talking to Sunamp about use of ASHP with their units.

 

While they talk about the Daikin HT heat pumps in some of their literature (which I assume is more costly/complex than a standard LT ASHP), they also recommend the use of some specific LT ASHP's that can provide a flow termperature of 65C. 

 

They suggest the "Daikin R32 LT ASHP" range,  but I think this only comes in a split system.  So, after some investigation I came across the LG Therma V R32 which can also suppy 65C, will be cheaper to install than a split system and comes in 5.5/7/9/12/14/16KW versions.  The COP at 65C is of course not particulary high, but a 2.5 ( @ 2C external) isn't terrible.  Wondering if anyone has used a LT 65C ASHP with Sunamp in practice?

 

Looking at potentially using 2 Sunamps in parallel to ensure both very good capacity but also a good flow rate.  
 

Wondering if there is any way to charge Sunamp to say 60% only with grid electircity during the day but allow it to be charged 100% with PV or E7?  To achieve the same PV-only buffer @ProDave mentioned that he achieves by only heating UVC to 48C and PV heating it further.

 

 

[Jeremy Harris]

Sadly the Sunamp gives no indication of its state of charge, so there's no way of knowing if it's at, say, 60% at all.  It's a significant issue, in my view, as not knowing what the thing is doing is one of the single most frustrating aspects of having one.  Mine lives with the cover of the controller off, so at least I can see the status LEDs on the control board (I'm not recommending that anyone do this, BTW).

 

Flow rate is not a worry at all with just a single Sunamp, now that they have increased the pipe size to 22mm and increased the performance of the internal heat exchanger (relative to the original Sunamp PV).  They are capable of delivering pretty good flow rates, at least as high as the largest combi boilers that are available, and on a par with an unvented hot water cylinder, so it may well make more sense to just fit a single, larger, unit.

[PeterW]

43 minutes ago, JSHarris said:

Mine lives with the cover of the controller off, so at least I can see the status LEDs on the control board

 

Just a thought - could you not use something like a fibre optic light pipe to extend the status LED ..? As usual, cheaper in the US than here ...

[Jeremy Harris]

4 minutes ago, PeterW said:

 

Just a thought - could you not use something like a fibre optic light pipe to extend the status LED ..? As usual, cheaper in the US than here ...

 

 

Yes, I did buy some optical fibre and meant to have a go at rigging up something to hold fibres over the LEDs so that I could route the light out to an external display panel.  I just haven't got around to doing it yet...

[Eileen]

We have a UNiQ eDual12 pcm58 which we use with a myenergi Eddi. We had a lot of early problems, partly poor communication with Sunamp (now a lot better) and partly with the controller, now replaced. Once fixed we have been 100% solar powered with only one recent tepid shower because we  were seeing how long it would last without charging (4 days) So now all is happy with that, and a lot of thanks goes to JSHarris!

 

We also have 2 x Dual4 pcm34 batteries, heated by a low temp Daikin ASHP,  that went through the same problems as the pcm58 battery, but are now working with their new controllers, albeit never used in anger. In retrospect these were a mistake for various reasons (some ours), especially as each one was comfortably more expensive than the big battery. However, now we’ve reached the week when there is typically going to be insufficient solar to power the big battery and we’re starting to fire up the ASHP again for ufh, we’ll be experimenting with using the smaller batteries to preheat the water heading to the big battery. Will report back.....

 

(Situation is a new energy positive certified Passivhaus)

[joth]

10 minutes ago, Eileen said:

We have a UNiQ eDual12 pcm58 which we use with a myenergi Eddi. We had a lot of early problems, partly poor communication with Sunamp (now a lot better) and partly with the controller, now replaced. Once fixed we have been 100% solar powered with only one recent tepid shower because we  were seeing how long it would last without charging (4 days) So now all is happy with that, and a lot of thanks goes to JSHarris!

 

We also have 2 x Dual4 pcm34 batteries, heated by a low temp Daikin ASHP,  that went through the same problems as the pcm58 battery, but are now working with their new controllers, albeit never used in anger. In retrospect these were a mistake for various reasons (some ours), especially as each one was comfortably more expensive than the big battery. However, now we’ve reached the week when there is typically going to be insufficient solar to power the big battery and we’re starting to fire up the ASHP again for ufh, we’ll be experimenting with using the smaller batteries to preheat the water heading to the big battery. Will report back.....

 

(Situation is a new energy positive certified Passivhaus)

 

Thanks for sharing this feedback, a useful datapoint and sounds like things are improving on the service/support side. 

 

If you hadn't purchased the pcm34s, how would you plan to charge the pcm58 in winter? Direct from the immersion heater only, presumably at Economy 7 times? 

[Jeremy Harris]

17 minutes ago, Eileen said:

We have a UNiQ eDual12 pcm58 which we use with a myenergi Eddi. We had a lot of early problems, partly poor communication with Sunamp (now a lot better) and partly with the controller, now replaced. Once fixed we have been 100% solar powered with only one recent tepid shower because we  were seeing how long it would last without charging (4 days) So now all is happy with that, and a lot of thanks goes to JSHarris!

 

We also have 2 x Dual4 pcm34 batteries, heated by a low temp Daikin ASHP,  that went through the same problems as the pcm58 battery, but are now working with their new controllers, albeit never used in anger. In retrospect these were a mistake for various reasons (some ours), especially as each one was comfortably more expensive than the big battery. However, now we’ve reached the week when there is typically going to be insufficient solar to power the big battery and we’re starting to fire up the ASHP again for ufh, we’ll be experimenting with using the smaller batteries to preheat the water heading to the big battery. Will report back.....

 

(Situation is a new energy positive certified Passivhaus)

 

 

Really glad to hear it's all working well (and sorry for the delay in replying to the PM - my inbox here seems to fill up quickly!).

 

I can confirm that since Sunamp resolved the issues with the controller firmware and sensor chain, our Sunamp UniQ eHW has been working very well indeed.  The difference between the way it performs now, and the way it performed before the controller change is like night and day.

 

We're now finding that our Sunamp is charging a bit during the E7 boost time, as our PV production does the usual and falls off the October cliff, although we've pretty much had 100% solar provided hot water until fairly recently, so we can't complain.  We're on target for a sub-£80 annual hot water cost, which seems pretty reasonable, as we don't skimp on using hot water at all.

[Eileen]

Yes, Joth. First choice would still be solar, but it comes after our 10kwh electric battery in the food chain so there won’t be many days like that over winter. Timed economy7 or 10 slots would be the fallback, and we think the pcm34s are overkill.

 

[joth]

@Eileen  another question I'd be curious what Daikin ASHP model/version you have, and if it is setup or supports cooling as well as heating? (i.e. is it reversible?)

 

(I'm a bit lost in their model numbering, I currently have EBLQ-07CAV3 as a baseline for my specification/pricing comparison, I also see EDLQ-07CAV3 mentioned in their brochures...  I think the EBLQ has cooling option and EDLQ is heating only, but it's really not clear. )

 

Also the newer  "Daikin Altherma 3" also looks pretty ideal for Sunamp system, as supports cooling, heating and DHW at 65°C in a single stage LT heat pump, and with a built-in 2x3kW backup/boost immersion heater. Only snag is it's a split unit, so the maintenance savings from moving from UVC to sunamp are completely wiped out by adding a refrigerant loop around the house.  (But, at least is is R32) 

 

 

Edited November 8, 2019 by joth

[Eileen]

I’m on a train so can’t get the actual number, but it’s a middle sized EDLQ (I think, so will confirm when back). It’s split with the external part in the garden maybe 30 metres away. Only used in winter primarily for ufh and secondarily for the low temp Sunamps.

[Dan F]

On 08/11/2019 at 16:04, joth said:

Also the newer  "Daikin Altherma 3" also looks pretty ideal for Sunamp system, as supports cooling, heating and DHW at 65°C in a single stage LT heat pump, and with a built-in 2x3kW backup/boost immersion heater. Only snag is it's a split unit, so the maintenance savings from moving from UVC to sunamp are completely wiped out by adding a refrigerant loop around the house.  (But, at least is is R32)

 

I took at look at this ASHP also and had the same concern. The other thing with using ASHP to charge Sunamp is that any savings in heat loss (which actually helps heat house in winter) are wiped out by the lower COP of heating to 65C rather than 55C.

 

I'm told Sunamp are testing a Monobloc LT ASHP, but I thnk I'd still stuggle to justify using ASHP+Sunamp given lower COP and higher capital costs. 

[Nickfromwales]

24 minutes ago, Dan Feist said:

I'm told Sunamp are testing a Monobloc LT ASHP, but I thnk I'd still stuggle to justify using ASHP+Sunamp given lower COP and higher capital costs.

It would come into it's own if being used in conjunction with high temp space heating + DHW, with SA being used as a heat bank for load-shifting off E7 / 10 / other, but yes, it's a difficultt sale at the price ticket that results in trying to combine the two.

I'm much more of an advocate of SA = DHW, and then space heating gets met as and how best practicable. Let's not forget, however, that these types of installations are off-set by RHI payments, which does change things in anything less than a well-performing dwelling / poor EPC rating as that equals higher payments to go towards off-setting the capital expenditure. 

[joth]

 

26 minutes ago, Dan Feist said:

The other thing with using ASHP to charge Sunamp is that any savings in heat loss (which actually helps heat house in winter) are wiped out by the lower COP of heating to 65C rather than 55C.

 

 

 It claims COP of 3.5 at 55ºC, so is it really so bad at 65ºC?

 

The attraction of the SunAmp is lower heat loss and space saving.

Sure, any system heat loss does not go "to waste" in winter, but in summer it does, and even if it is useful for space heating in winter I'd like to see if I can have sourced from ASHP (even at a COP of 2)  than from a resistive element.

 

[Dan F]

56 minutes ago, joth said:

It claims COP of 3.5 at 55ºC, so is it really so bad at 65ºC?

 

The attraction of the SunAmp is lower heat loss and space saving.

Sure, any system heat loss does not go "to waste" in winter, but in summer it does, and even if it is useful for space heating in winter I'd like to see if I can have sourced from ASHP (even at a COP of 2)  than from a resistive element.

 

I don't have the Daikin datasheet, but the with LG 9KW R32 monobloc model I've been looking at the difference in COP between 55C and 65C depends on lot on exterior temperature.  It's minimal when it's cold outside, but more significant otherwise:

2C Outdoor:    2.55@55C   2.15@65C

7C Outdoor:    2.66@55C   2.40@65C

10C Outdoor:    3.18@55C   2.55@65C

15C Outdoor:    3.73@55C   2.80@65C

18C Outdoor:    3.93@55C   2.95@65C

 

The flow rate is 25% less @ 65C also on this model, so the recovery rate of Sunamp wouldn't be at good (even taking into account the addition 10C I beleive)

 

We ran some calculations and the loss in COP cancelled out any saving from heat loss. Agree on space saving, but a slimline 300/400L doesn't take up much more floor space that an Sunamp.  Also, we considered that if we wanted to ensure high flow rate we'd actually need 2 Sumap's pushing up the capital cost even higher.

 

We've decided to go UVC for now based on the above, but will revist in the spring based on further information or product releases (e.g. a PCM48).

 

 

Edited November 12, 2019 by Dan Feist

[Eileen]

@Joth - it's a Daikin Altherma low temp split EHBH08CB3V indoors and ERLQ006CV3 outdoors 

 

It needs to be EHBX for heating /cooling

Edited November 13, 2019 by Eileen

[scottishjohn]

On 13/09/2019 at 17:52, Ed Davies said:

f you're going to have a buffer tank for your UFH anyway for flow/cycling reasons then using that to preheat the DHW might make sense. I have similar thoughts about a pre-heat buffer tank heated by solar thermal followed by a Sunamp heated by PV. That'd allow the solar thermal to operate at lowish temperature where it works more efficiently and the PV to do the just the last bit of heating of the DHW up to the use temperature where you want to use the least electricity for the purpose possible.

I am a great lover of solar thermal  and spent many many hours and days trying to devise a system to provide all the heat for  a modern  house 

I ran 40 panels for 20 years 

the problem is getting  big enough storage at a reasonable price-  

the cost to build such a tank makes it not an economic choice 

 

so i see what you are wanting to do --just make sure you have a large enough buffer tank 

 

there are very few days  ALL YEAR ROUND when you cannot get 30c-40c+ if pump speed is controlled  correctly for panel area

  Tank  must be big enough to take the high temps you will get  on a good summers day  

If you want to limit summer output --hang them vertically on a wall --maybe with a shade device-- to limit summer output in middle of the day 

 and so  you only get best when sun is at low angle in winter when the shade device will do nothing 

 

 I had a sensor pack up and the result was the foam insulation melted off the copper transfer pipes --thats over 170c!!!

 i have  studied this for a long time and its just not viable  to provide all heat for year without mega size mega insulated tank -- so not cost effective 

 

maybe if you could find an old     milk tanker and  drive it into  deep a hole in the garden  and surround with insulation --it might work out economic -- LOl

building concrete or grp  etc under the house like a basement  --just too expensive  --10k+

Edited November 14, 2019 by scottishjohn